--- a/ipc/mscom/FastMarshaler.cpp
+++ b/ipc/mscom/FastMarshaler.cpp
@@ -98,17 +98,17 @@ FastMarshaler::InternalRelease()
 DWORD
 FastMarshaler::GetMarshalFlags(DWORD aDestContext, DWORD aMshlFlags)
 {
   // Only worry about local contexts.
   if (aDestContext != MSHCTX_LOCAL) {
     return aMshlFlags;
   }
 
-  if (!IsCallerExternalProcess()) {
+  if (IsCallerExternalProcess()) {
     return aMshlFlags;
   }
 
   // The caller is our parent main thread. Disable ping functionality.
   return aMshlFlags | MSHLFLAGS_NOPING;
 }
 
 HRESULT